An anecdote — I recently upgraded an old NodeJS project written using v14 to 22. It used an old version of Svelte for the UI. It wasn’t too bad, took about 90 minutes to upgrade a bunch of Svelte 3 components to Svelte 5, with some assistance from Copilot.

This was with zero awareness of Svelte 5 (I only knew it was released — I wanted to upgrade because Node 14 is EOL now and I’d noticed some npm audit warnings.) So I feel I also learned something in the process.